Devices, systems, and methods for improving pelvic floor dysfunction

ABSTRACT

An apparatus for delivering an electrical microstimulator is provided. The apparatus comprises a handle having a handle body. An elongate delivery rod includes a delivery sheath for reciprocal movement with respect to the handle body. The delivery rod extends longitudinally from the handle body. A microstimulator docking feature is provided for selectively maintaining the electrical microstimulator on the delivery rod. The microstimulator docking feature includes at least one arm which engages the electrical microstimulator. An anchor tester is associated with the handle body for selectively sensing motion of the electrical microstimulator under influence of an applied predetermined longitudinal testing force. A method of delivering an electrical microstimulator to a target implant site of a patient&#39;s body is also provided.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 15/873,290, filed on 17 Jan. 2018, which claimspriority to the following provisional applications: U.S. ProvisionalApplication No. 62/446,983 filed on 17 Jan. 2017, U.S. ProvisionalApplication No. 62/506,814 filed on 16 May 2017, and U.S. ProvisionalApplication No. 62/580,540, filed on 2 Nov. 2017; all of theaforementioned applications are incorporated by reference in theirentirety, for all purposes. This application also relates to U.S. patentapplication Ser. No. 15/873,323, filed on 17 Jan. 2018, the entirety ofwhich is incorporated by reference herein, for all purposes.

TECHNICAL FIELD

The present disclosure relates to electrical microstimulators, deliverysystems for implanting electrical microstimulators, and methods ofimproving pelvic floor dysfunction and peripheral nerve pain.

BACKGROUND

Overactive bladder (OAB), a type of pelvic floor disorder, is a symptomcomplex that is characterized by urinary urgency, with or withouturgency-associated urinary incontinence. OAB is often associated withurinary frequency and nocturia in the absence of infection or otherobvious pathology.

Current treatment options for OAB include behavioral therapy,pharmacotherapy, and neuromodulation. Behavioral therapies includelifestyle changes, bladder training, and pelvic floor muscle training.Pharmacological agents approved for use in OAB include anticholinergics,beta3-receptor agonists and detrusor injections of neuromuscularblockers. Anticholinergics inhibit the binding of acetylcholine to themuscarinic receptors in the detrusor muscle, thereby suppressinginvoluntary bladder contractions. This results in an increase in bladdervolume voided and a decrease in micturition frequency, sensation ofurgency, and the number of urge incontinence episodes. Beta3 adrenergicagonists elicit a direct inhibition of afferent nerve firing independentof the relaxing effects on bladder smooth muscle. Detrusor injections ofbotulinum neurotoxin type A, a neuromuscular blocker, may be consideredfor adults with OAB who cannot use or do not adequately respond toanticholinergic medication.

In terms of neuromodulation, the two most commonly utilized techniquesare sacral nerve stimulation (SNS) and percutaneous tibial nervestimulation (PTNS). SNS provides continuous stimulation of the sacralnerve through surgical implantation of a permanent electrode and apermanent pulse generator while PTNS uses intermittent stimulation ofthe tibial nerve at the ankle with no permanently implanted lead orstimulator. SNS procedures involve making a midline sacral incision andcarrying the incision down to the level of the lumbodorsal fascia, whichis opened sharply from the midline. The underlying paravertebral musclesare separated or divided, and the sacral periosteum is identified. Anelectrical lead is ultimately inserted through the appropriate sacralforamen to lie adjacent to the sacral nerve and the lead is sutured tothe periosteum to prevent lead migration. An example of PTNS involvespercutaneously inserting a fine-gauge needle just above the ankle nextto the tibial nerve and placing a surface electrode on the foot. Theneedle and electrode are connected to a low-voltage stimulator thatdelivers stimulation pulses to the tibial nerve. PTNS therapy isprovided in an outpatient clinic setting and, in general, is performedinitially for 30 minutes weekly for 12 weeks, followed by occasionaltreatments as needed based on patient symptoms. An advantage of SNS andPTNS is that the electrode is placed close to the target nerve providingdirect stimulation of the nerve and requiring less energy consumption.

Recent studies have also been carried out regarding the efficacy oftranscutaneous tibial nerve stimulation with the use of externalelectrodes. Electrodes are applied near to the ankle where thetibial/sural nerve is located. It is believed that the electricalstimulation can penetrate the skin delivering tibial nerve stimulationin the same way as PTNS, but without the need for a needle electrode.Transcutaneous tibial nerve stimulation is completely non-invasive, withsurface electrodes connected to a battery operated stimulator andapplied to an appropriate site of the body. Such treatment generallydoes not require regular patient visits at clinics and usually isself-administered at home, which is convenient for the patient.

SUMMARY

In an aspect, an apparatus for delivering an electrical microstimulatoris provided. The apparatus comprises a handle having a handle body. Anelongate delivery rod includes a delivery sheath for reciprocal movementwith respect to the handle body. The delivery rod extends longitudinallyfrom the handle body. A microstimulator docking feature is provided forselectively maintaining the electrical microstimulator on the deliveryrod. The microstimulator docking feature includes at least one arm whichengages the electrical microstimulator. An anchor tester is associatedwith the handle body for selectively sensing motion of the electricalmicrostimulator under influence of an applied predetermined longitudinaltesting force.

In an aspect, a method of delivering an electrical microstimulator to atarget implant site of a patient's body. The method comprises providinga delivery tool. The delivery tool includes a handle having a handlebody. An elongate delivery rod includes a delivery sheath for reciprocalmovement with respect to the handle body. The delivery rod extendslongitudinally from the handle body. A microstimulator docking featureincludes at least one arm. The arm selectively engages and releases theelectrical microstimulator under influence of the delivery sheath. Ananchor tester is associated with the handle body. The electricalmicrostimulator is engaged with the at least one arm of themicrostimulator docking feature. The delivery sheath is manipulated tomaintain the electrical microstimulator on the delivery rod with thearm. The electrical microstimulator, maintained on the delivery rod bythe microstimulator docking feature, is carried to the target implantsite. With the electrical microstimulator at least partially maintainedon the delivery rod by the microstimulator docking feature, apredetermined longitudinal testing force is applied to the electricalmicrostimulator via the anchor tester. Motion of the electricalmicrostimulator under influence of the applied predeterminedlongitudinal testing force is sensed to determine anchoring security ofthe electrical microstimulator at the target implant site. Anchoringsecurity of the electrical microstimulator at the target implant site iscommunicated to a user of the delivery tool. The electricalmicrostimulator is at least partially released from the delivery rod atthe target implant site by manipulation of the delivery sheath torelease the electrical microstimulator from the at least one arm of themicrostimulator docking feature.

In an aspect, an apparatus for delivering an electrical microstimulatoris provided. The apparatus comprises a handle having proximal and distalhandle ends longitudinally separated by a handle body. The distal handleend includes a rod aperture. An elongate delivery rod has proximal anddistal rod ends longitudinally separated by a rod body and includes adelivery sheath for reciprocal movement at least partially between theproximal and distal rod ends. At least a portion of the rod body extendslongitudinally through the rod aperture. A microstimulator dockingfeature is associated with the delivery rod. The microstimulator dockingfeature selectively maintains the electrical microstimulator at thedistal rod end. The microstimulator docking feature includes at leastone arm which selectively engages the electrical microstimulator underinfluence of an arm-urging force applied by the delivery sheath. Ananchor tester is associated with the handle body. The anchor testerselectively senses motion of an electrical microstimulator at leastpartially engaged with the microstimulator docking feature, underinfluence of an applied predetermined longitudinal testing force.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding, reference may be made to the accompanyingdrawings, in which:

FIG. 1 is a flow diagram indicating steps of a method of improvingpelvic floor dysfunction according to an embodiment of the presentdisclosure;

FIG. 2 is a flow diagram indicating steps of a method of improvingpelvic floor dysfunction according to an embodiment of the presentdisclosure;

FIG. 2A is a block diagram of exemplary components of a system accordingto an embodiment of the present disclosure;

FIG. 2B is a schematic illustration of a stimulation profile for nervelocalization according to an embodiment of the present disclosure;

FIG. 3 depicts schematic illustrations of EEG signals corresponding tostimulation signals that are applied by a microstimulator or deliverytool as the microstimulator is being inserted through tissue accordingto an embodiment of the present disclosure;

FIG. 4 is a schematic illustration of the lower portion of a patient'sleg indicating a region to which a microstimulator can be implantedaccording to an embodiment of the present disclosure;

FIG. 5 is a schematic illustration of a site in connective tissue belowskin and above deep fascia where a delivery tool can be advanced and amicrostimulator positioned according to an embodiment of the presentdisclosure;

FIG. 6 is a perspective view of a microstimulator according to anembodiment of the present disclosure;

FIG. 7 is a perspective view of a microstimulator with fixation membersin a non-deployed position according to an embodiment of the presentdisclosure;

FIG. 8 is a perspective view of the microstimulator of FIG. 7 with thefixation members in a deployed position according to an embodiment ofthe present disclosure;

FIG. 9 is a perspective view of a microstimulator with fixation membersin a non-deployed position according to an embodiment of the presentdisclosure;

FIG. 10 is a perspective view of the microstimulator of FIG. 9 with thefixation members in a deployed position according to an embodiment ofthe present disclosure;

FIG. 11 is a perspective view of the distal end of a microstimulatoraccording to an embodiment of the present disclosure;

FIG. 12 is a perspective view of the distal end of a microstimulatoraccording to an embodiment of the present disclosure;

FIG. 13 is a perspective view of the distal end of a delivery toolaccording to an embodiment of the present disclosure;

FIG. 14 is a bottom view of a delivery tool and a microstimulatorinserted therein according to an embodiment of the present disclosure;

FIG. 15 is a partial cross-sectional view of a delivery tool accordingto an embodiment of the present disclosure;

FIGS. 16A-E are sample waveforms that could be used to determine atarget implant site to which a microstimulator is anchored;

FIGS. 17-21 are flow diagrams indicating steps of a method ofdetermining a target implant site in which to implant a microstimulatoraccording to embodiments of the present disclosure;

FIG. 22 is a block diagram of components of a system used to determine atarget implant site to which a microstimulator is anchored;

FIG. 23 is a schematic top view of an example insertion tool accordingto an embodiment of the present disclosure;

FIGS. 24-31 are schematic side perspective views, and correspondingpartial detail views, of the insertion tool of FIG. 23 during an exampleuse sequence;

FIG. 32 is a schematic top perspective view of an example insertion toolsimilar to that of FIGS. 23-31;

FIG. 33 is a schematic side view of the insertion tool of FIG. 32;

FIG. 34 is a schematic front perspective view of the insertion tool ofFIG. 32;

FIG. 35 is a schematic top perspective partial view of the insertiontool of FIG. 32;

FIG. 36 is a schematic top perspective partial view of the insertiontool of FIG. 32;

FIG. 37 is a is a schematic top perspective partial view of theinsertion tool of FIG. 32;

FIG. 38 is a schematic top perspective partial view of the insertiontool of FIG. 32;

FIGS. 39-40 schematically illustrate an example partial sequence of useof the insertion tool of FIG. 32; and

FIG. 41 is a flowchart of an example sequence of use of the insertiontool of FIG. 32.

DESCRIPTION OF ASPECTS OF THE DISCLOSURE

The invention comprises, consists of, or consists essentially of thefollowing features, in any combination.

The present disclosure generally relates to methods, devices and systemsfor improving pelvic floor dysfunction in a patient suffering therefromby electrically modulating neural tissue in a minimally invasive fashionusing an electrical microstimulator. A “microstimulator” as used hereinhas a width of greater than 0 mm and less than approximately 7millimeters (mm), a height of greater than 0 mm and less thanapproximately 6 mm and a length of greater than 0 mm and less thanapproximately 30 mm.

As used herein with respect to a described element, the terms “a,” “an,”and “the” include at least one or more of the described elementincluding combinations thereof unless otherwise indicated. Further, theterms “or” and “and” refer to “and/or” and combinations thereof unlessotherwise indicated. It will be understood that when an element isreferred to as being “over,” “on,” “attached” to, “connected” to,“coupled” with, “contacting,” “in communication with,” etc., anotherelement, it can be directly over, on, attached to, connected to, coupledwith, contacting, or in communication with the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly over,” “directly on,” “directlyattached” to, “directly connected” to, “directly coupled” with,“directly contacting,” or in “direct communication” with anotherelement, there are no intervening elements present. An element that isdisposed “adjacent” another element may have portions that overlap orunderlie the adjacent element. By “substantially” is meant that theshape, configuration, or orientation of the element need not have themathematically exact described shape, configuration or orientation butcan have a shape, configuration or orientation that is recognizable byone skilled in the art as generally or approximately having thedescribed shape, configuration, or orientation.

Referring to FIG. 1, in an embodiment, a method (100) of improvingpelvic floor dysfunction can comprise inserting a microstimulatorthrough skin of a patient's leg (step 102) and advancing themicrostimulator to an area of the patient's leg (step 104). Themicrostimulator has a re-deployable fixation member as described in moredetail below. The area of the patient's leg can be on the medial side ofthe patient's leg below or at the knee and posterior to the tibia; orimmediately below or at the medial condyle of the tibia. Themicrostimulator can be advanced to region 11 as illustrated in FIG. 4.Method 100 can further include positioning the microstimulator at atarget implant site adjacent to a target nerve associated with pelvicfloor function (step 106). In certain embodiments, the target implantsite is above deep fascia and below the skin. Method 100 can furthercomprise anchoring re-deployable fixation member of the microstimulatorto the target implant site (step 108). In certain embodiments, themicrostimulator is anchored above deep fascia and not to a layer of deepfascia (such as not affixing the microstimulator to the superficialsurface of the deep fascia tissue layer). Once the microstimulator hasbeen anchored to the target implant site, method 100 can comprisedelivering a therapy electrical signal to the target nerve to improvepelvic floor dysfunction (step 110). The therapy electrical signal canmodulate the target nerve by increasing or decreasing neuronal activity.As such, the therapy electrical signal can be an excitatory orinhibitory stimulation signal or a combination thereof. The therapyelectrical signal may also mask, alter, override, or restore neuronalactivity.

Referring to FIG. 2, in an additional or alternative embodiment, amethod of improving pelvic floor dysfunction (200) can compriseidentifying a target implant site to implant the microstimulator and asurgical pathway to reach the target implant site (step 202). The targetimplant site is adjacent to a target nerve associated with pelvic floorfunction. The target implant site can be determined, for example, usingultrasound, external skin electrodes, anatomical landmarks, or otherimaging or stimulating techniques. Visualization or localization of thetarget nerve as an initial step can be used to guide a clinician inselecting an incision site. After locating the target implant site andthe surgical pathway to the target implant site, method 200 can compriseinjecting a local anesthetic at an incision site and along the pathwayto the target implant site (step 204). This can be done by inserting asyringe to the implant target location along the pathway to the implanttarget location and slowly injecting anesthetic while removing thesyringe, or with a syringe with multiple exit ports along the lengththat distribute anesthetic along the entire pathway.

At step 206, a skin incision can be created. In particular and withadditional reference to FIG. 5, microstimulator 10 can be insertedthrough skin tissue by incising outer skin layer 12 using, for example,a standard scalpel or an incising edge or blade of a delivery tool. Theincision is preferably minimal in size to tightly accommodatemicrostimulator 10. For example, the length of the skin incision can beapproximately equal to the width of an incising end of a delivery toolto provide an incision just large enough to insert microstimulator 10 orthe distal end of delivery tool 20 used to deploy microstimulator 10.

At step 208, method 200 can comprise advancing the microstimulator alongthe surgical pathway to the target implant site. As illustrated in FIG.5, microstimulator 10 can be inserted and advanced subdermally viadelivery tool 20 to the target implant site. The delivery tool can havea flexible tip and/or a blunt tip (as described in more detail below) sothat it can be advanced at a shallow angle until deflected by deepfascia layer 14 and thereby to the target implant site that is abovedeep fascia layer 14 as schematically illustrated in FIG. 5. Such aflexible and/or blunt tip of the microstimulator can allow placement ofthe microstimulator as close as possible to the deep fascia whileremaining within the safest tissue region. Other ways in which deepfascia can be detected and/or avoided are described below. When adelivery tool advances a microstimulator through tissue above deepfascia, a tunnel is created such that a tissue pocket extends in thepatient's tissue from the incision site to the target implant site. Sucha tunnel can be filled leaving only a tight pocket within which themicrostimulator can reside. The tissue pocket can be just large enoughto receive the microstimulator. The tunnel can be filled with a collagenmatrix, gel or similar material. Such a material can contain wound ortissue repair substances to facilitate tissue healing. The tunnel canadditionally or alternatively be mechanically pinched together andclosed using a stitch, clip, staple or other closure device.

With further reference to FIG. 5, method 200 can further includepositioning microstimulator 10 at the target implant site (step 210). Asmentioned above, the target nerve is a nerve associated with pelvicfloor function. In certain embodiments, the target implant site is abovedeep fascia 14 adjacent to a target nerve, such as target nerve 18.Exemplary target nerves are tibial nerve 18 (including the posteriortibial nerve), a saphenous nerve, a cutaneous branch of the tibialnerve, a cutaneous branch of the saphenous nerve, or combinationsthereof. The target nerve can be two or more nerves and as used herein“a target nerve” can include a plurality of nerves. In certainembodiment, a target nerve is the tibial nerve (or a cutaneous branch ofthe tibial nerve) and the saphenous nerve (or a cutaneous branch of thesaphenous nerve).

Regarding step 212, capture or localization of the target nerve can beconfirmed. For example, using either electrodes located on themicrostimulator, separate electrodes on the delivery tool (also referredto as an “insertion tool” herein), and/or transcutaneous (surface)electrodes, electrical stimulation can be performed and activation ofthe target nerve can be sensed. Sensing can be performed by externalsensors monitoring ENG, EMG, or evoked potentials activity; or patientmovement. For example, stimulation electrodes on the tip of the deliverytool can evoke action potentials in the tibial nerve that are measuredvia an EMG as a muscle reflex on the sole of the foot. The sensors canbe placed anywhere on the patient's body that is innervated by thetarget nerve. For instance, the sensors can alternatively be placed onthe sole of the patient's foot to detect EMG activity of the Flexorhallucis brevis, Flexor digitorum brevis, or Flexor digiti minimi brevisof the foot, for example. As the delivery tool is inserted and advancedthrough tissue, the sensors can continuously sense EMG activity of amuscle innervated by the target nerve as stimulation pulses aredelivered by the stimulation electrodes. Detection of a maxima (a maximais the maximum value of a signal that occurs within a function of agiven algorithm and not necessarily the maximum signal possible) in ENG,EMG, or evoked potentials activity indicates that the microstimulator ismost proximate to the target nerve. Such a location when accomplished atthe lowest strength of the stimulation pulse (e.g. amplitude) achievesan implant procedure that causes the least patient discomfort, andresults in an implant site that provides therapeutic stimulation at thelowest power consumption requirements. In other words, a method canemploy an algorithm that determines nerve capture so that when an ENG,EMG, or evoked potential signal is detected, the stimulation strengthcan be commensurately adjusted to find an implant site where a maxima inENG, EMG, or evoked potential signal is elicited with minimalstimulation pulse strength. By dynamically adjusting the balance betweenan ENG, EMG, or evoked potential signal and stimulus strength, thetarget implant site can be determined while avoiding a painful motor orsensory response from the patient, such as a painful muscle contraction.FIG. 3 provides a schematic illustration of a microstimulator movingtowards a target nerve and the corresponding stimulation signal appliedby electrodes, the corresponding EMG signal, and the correspondingindication on the device or insertion tool regarding the EMG signal(“Detecting;” “Baseline;” “Optimal;” and “Overshoot”) described in moredetailed below.

Regarding transcutaneous stimulation to localize a target nerve, such amethod can be used in addition to or instead of the target nervelocalization steps described above. For example, EMG recordingelectrodes can be applied to a portion of the patient's body innervatedby the target nerve. For example, if the target nerve is the tibialnerve, the EMG electrodes can be applied to the bottom of the patient'sfoot adjacent to the abductor hallucis muscle on the bottom of thepatient's foot. Stimulation pulses can be applied, via transcutaneouselectrodes, to a portion of the patient's body adjacent to the targetnerve. For example, if the target nerve is the tibial nerve,transcutaneous electrodes can be placed on the patient's ankle. An EMGsignal can be detected via the recording electrodes. Detection of an EMGsignal can indicate that the target nerve has been localized and thetarget medical device implant site has been identified. A mechanicaltemplate can be used to mark a tunneling path and incision point. Anappropriate skin incision can then be made and an insertion tool can beinserted through the incision towards the target medical device implantsite. Once the target medical device implant site has been reached, themicrostimulator can be released from the insertion tool and anchored tothe medical device implant site.

An exemplary system that can be used to localize a target nerve,including transcutaneous stimulation, is provided in FIG. 2A. Insertiontool 1000 includes a stimulation output stage 1002 and an evokedpotential input stage, such as EMG input stage 1004, a microprocessor1006, a user interface 1008 and a power source 1010. Although thestimulation output stage is illustrated as being a part of the insertiontool, it can also be part of the microstimulator. To perform nervelocalization, the microprocessor can send a control signal to thestimulation output stage to send a stimulation pulse to the patient'stissue via stimulation electrodes 1012. Such stimulation electrodes canbe placed on the patient's ankle 1014 for example. If the electrodes arein the vicinity of the target nerve, such as the tibial nerve 1016, anaction potential will be created that travels along the tibial nerve toa muscle in the patient's foot 1018 innervated by the tibial nerve, suchas the abductor hallucis muscle, for example. EMG recording electrodes1020 can be placed on the surface of the skin above the abductorhallucis muscle, for example. The EMG input stage 1004 can sample rawEMG data 1022 for a short period of time (such as, for example,approximately 16 milliseconds) after the end of each stimulation pulse.The raw EMG data can then be analyzed by the microprocessor to firstdetermine whether an EMG signal is present, and if it is, to alsodetermine the strength of the EMG signal. Using information about theEMG that resulted from a previous stimulation pulse, the microprocessorcan adjust the parameters for the next stimulation pulse 1024. The userinterface, which can include pushbuttons 1008 a, LED/LCD indicators 1008b, and or audio inputs and outputs, can also be updated to reflect thestatus of nerve localization.

The EMG input stage, for example, can use an analog front end integratedcircuit with a 24-bit analog-to-digital circuit that can be set toapproximately 4,000 or 8,000 samples per second, for example. The rawEMG signals can be processed using fast fourier transform (FFT) tomeasure the presence and strength of the EMG signal. This can allowpulse-by-pulse control of the stimulation, which adds to the robustnessof the nerve localization methodology.

A relevant aspect of nerve localization can be the stimulation profile.For example, the angle-of-approach to the target nerve can have animpact on the ability to recruit the target nerve, such as the tibialnerve. For example, without wishing to be bound by theory, certainangles-of-approach may hyperpolarize a region of the tibial nerve (asopposed to the desired depolarization), potentially blocking actionpotentials from traveling to the abductor hallucis muscle. To avoid thispossible issue and to allow the nerve localization to work robustlyregardless of the angle-of-approach, an insertion tool can be used withthe stimulation profile 2000 depicted in FIG. 2B. As can be seen fromthis figure, the polarity of stimulation is alternated from pulse topulse. This means that if hyperpolarization is blocking actionpotentials during a cathodic pulse, the change in polarity for the nextanodic pulse should prevent hyperpolarization in the same region,allowing action potentials to pass. The stimulation profile illustratedin FIG. 2B can be used for various ways of localizing a nerve asdescribed herein and is not limited to nerve localization viatranscutaneous stimulation.

Transcutaneous nerve localization, as disclosed herein, can provideseveral advantages compared to other neural recording systems. Forexample, most neural recording systems use blanking, amplification,filtering, and/or averaging to measure EMG signals. An insertion tool,as described above, does not necessarily require such techniques.Instead, disclosed methods can involve collecting raw EMG data using onechannel of input and a 24-bit analog-to-digital converter, for example.The data collection occurs during a short window of time (such as, forexample, approximately 16 milliseconds) after each pulse. When thetarget nerve is the tibial nerve, low-level EMG signals can be detectedat the surface of the foot even before a toe twitch is elicited. Inaddition, this technique is so fast that it can allow the stimulationparameters to be adjusted before the next pulse, meaning that the nervelocalization methodology can be fast and extremely responsive.

The EMG processing technique, as described above, is also different fromother neural recording systems. For example, raw EMG data can beprocessed using FFT with no pre-processing. Post-processing integrationof the FFT results can also produce a single number that indicates thestrength of the EMG signal. For example, integrating the FFT resultsbetween 125-500 Hz can provide a reliable measure of the EMG strength.This is useful for several reasons. For example, it provides EMGstrength feedback when determining how well the EMG recording electrodesare placed on the foot, for example. Further, it provides usefulinformation during nerve localization when trying to keep the EMGresponse from toe twitch, for example, to a minimum.

The pulse-by-pulse control during nerve localization also providesadvantages. For example, as the clinician is tunneling the insertiontool towards the target nerve, such as the tibial nerve, the nervelocalization methodology preferably responds as quickly and robustly aspossible. The clinician needs instant feedback as the tool approachesthe nerve, since distances as small as a few millimeters can have alarge effect on nerve response. Given the methodology described herein,it is possible to do pulse-by-pulse control with stimulation frequenciesas high as 50 Hz, for example.

Pulse-by-pulse control is also relevant to minimize the impact on thepatient since a goal of therapy is for the patient to feel as littlepain as possible during the implant procedure or during localization ofthe target implant site. As the insertion tool, as described herein,approaches the target nerve, such as the tibial nerve, it is preferableto turn down the stimulation amplitude as quickly as possible to reducethe amount of afferent (sensory) fibers that are activated. In addition,it is preferable to minimize the amount of toe twitch in the case oftibial nerve stimulation, for example. Not only can toe twitch beuncomfortable for the patient, the movement can make it more difficultfor the clinician to tunnel the insertion tool accurately.

As described above, for tonic stimulation, the angle at which theinsertion tool is tunneled towards the nerve can make a difference inthe ability to recruit the target nerve. Therefore, it has beendetermined as disclosed herein that a stimulation profile thatalternates the polarity of the pulse from one pulse to the next ispreferable. This means that if action potentials are being blocked forone polarity, the action potentials will not be blocked during thesubsequent pulse of opposite polarity.

Transcutaneous nerve localization has several additional advantages.During the implant procedure, transcutaneous nerve localization can beused to identify the target location for the microstimulator or thetarget medical device implant site prior to creating a stab incision.This may provide more confidence than simply using a mechanical templateto identify the target implant site. A transcutaneous method can also beused as a simple trial to determine whether a patient is a candidate foran implant. Further, a transcutaneous method can be used to identifyideal electrode locations for a surface stimulator that could be usedinstead of an implant. Transcutaneous nerve localization can be used formany applications unrelated to tibial nerve stimulation, which has onlybeen provided as an exemplary embodiment. For example, it could be usedto map nerves prior to surgery, allowing doctors to mark areas to avoidwhile cutting.

Moreover, methodologies as described herein are in contrast to othertypes of nerve localization methods where EMG signals are measured whilea patient is under general anesthesia, in which case, a clinician is notnecessarily concerned with a patient perceiving pain. In such instances,a magnitude of stimulation strength is applied to recruit a targetnerve, with no regard to the number of motor units (a motor unit is madeup of a motor neuron, and the muscle fibers innervated by that motorneuron's axonal terminals) activated, power consumption by stimulatingelectrodes, or proximity of stimulating electrodes to the target nerve.In forms of PTNS, a clinician can ramp up the strength of stimulationuntil achieving a motor response in the patient's big toe or the bottomof the patient's foot, for example. The clinician then reduces thestrength of the stimulation to obtain a therapeutic delivery signal. Incertain methods as disclosed herein, a target nerve is localized beforethe patient experiences any undesirable or uncomfortable motor orsensory responses and, preferably, a minimum number of motor units, arerecruited and detected via an EMG. In certain methods as disclosedherein, target nerves can comprise mixed nerves (nerves with both motorand sensory neurons), pure motor, or pure sensory nerves. Such amethodology is also different from other nerve localization techniqueswhere the clinician is trying to achieve an implant location with adelivery tool or the implantable device by either getting as proximateto a target nerve as possible or avoiding contact with a target nerve.Methodologies as disclosed herein can locate a target nerve whileremaining a safe distance from the target nerve.

Referring again to FIG. 2, at step 214, a delivery tool can deploy afixation member (as described in more detail below) to anchor themicrostimulator at the target implant site, which can be connectivetissue above deep fascia. Sufficient anchoring can be verified, forexample, by gently pulling the delivery tool to test the strength of theanchor, or by force measurement confirming adequate microstimulatorresistance to movement is obtained (as described in more detail below).For example, to ensure that the microstimulator is securely anchored,the delivery tool or a portion of the delivery tool can be manipulatedproximally to determine if the fixation member disengages from thetarget implant site. If so, the fixation member can be released andre-deployed until it is determined that the microstimulator is securelyanchored to the target implant site. The microstimulator can bepositioned parallel, perpendicular or at any angle to the target nerve.

At step 216, sufficient nerve capture confirmation is performed, asdescribed in step 212. Nerve capture confirmation can be achieved bydelivering test stimulation pulses and measuring and/or observing astimulation response. If the proper stimulation location and anchoringstrength is verified, the microstimulator can be released and thedelivery tool can be removed (step 220). Alternatively, if thestimulation location and anchoring strength are not adequate, thefixation member can be released (disengaged from tissue) (step 220) andthe delivery tool can reposition the microstimulator (step 222). Steps210 through 216 can be performed until sufficient stimulation andanchoring are achieved.

Once sufficient stimulation and anchoring are achieved at step 216, themicrostimulator can be released or “undocked” from the delivery tool (asdescribed in more detail below) and the delivery tool can be removed(step 222). In certain embodiments, prior to release of themicrostimulator, the microstimulator can be programmed to deliver astimulation signal having pre-determined parameters, such as apre-determined intensity, that are deemed to have therapeutic benefits.The patient's response to such stimulation can be observed or detectedfor any painful or uncomfortable response. Gauging the sensationperceived by the patient before releasing the microstimulator from thedelivery tool can increase the probability of prescribed therapycompliance and decrease adverse effects due to stimulation. At step 224,the microstimulator can deliver a therapeutic electrical signal to thetarget nerve to improve pelvic floor dysfunction.

The above described methods are exemplary and other methods forimplanting a microstimulator to deliver a therapy signal to a targetnerve to improve pelvic floor dysfunction can include combinations andsub-combinations of the above-described steps, including the eliminationor addition of certain steps.

In certain methods of improving pelvic floor dysfunction as disclosedherein, a microstimulator can be implanted in a target implant site thatis above deep fascia adjacent to a target nerve associated with pelvicfloor function. Compared to SNS and PTNS procedures for treatingoveractive bladder (OAB), certain methods as disclosed herein involveimplanting a microstimulator further away from a target nerve andanchoring the microstimulator in randomly distributed connective tissue.For example, SNS and PTNS involve implanting or inserting an electrodedirectly adjacent to the target nerve and therefore such procedures havea greater probability of activating the target nerve. However, methodsand devices disclosed herein can deliver an efficacious electricaltherapy signal to the target nerve and can also securely and safelyfixate the microstimulator to looser connective tissue of the targetimplant site that is above deep fascia.

Regarding delivering an efficacious electrical therapy signal,electrical current delivered by the microstimulator can be steered toshape the stimulation field to ensure appropriate nerve capture. Forexample, a microstimulator can be used that has independentlyprogrammable electrodes that can each be activated, deactivated,programmed to deliver a certain percentage of electrical current, and/orhave independent current sources (stimulation channels) to customize,shape and steer the electrical current. Independently programmableelectrodes also allow the modulation to be directional in natureapplying an activation signal to only certain regions while sparingmodulation to others. Such directional electrodes allow for preciseselective modulation of the target nerve as well as allow steering ofthe electrical signal. Independently programmable electrodes also allowsimultaneous or sequential delivery of electrical signals to one or moretarget nerves with each electrical signal having stimulation parameters,such as frequency, amplitude, pulse width, specific to the target nerveto maximize therapy. A set of specific values for each stimulationparameter can constitute a program (for example 2 Hz, 10 mA, 150 usrespectively). Further, the microstimulator can be programmed to deliverat least two independent stimulation programs to the target nerve.

In addition to modulating the direction of the electrical signal, thedegree of activation that each electrode delivers can be adjusted. Forexample, the pulsing parameters of electrodes may be adjusted toinitiate, stop, increase, or decrease the pole combinations, energy,amplitude, pulse width, waveform shape, frequency, and/or voltage orother pulsing parameter to adjust the degree of modulation deliveredthereby. Additionally, the shape of the electric field can varycorresponding to the power applied, the number and arrangement ofelectrodes, and particular shapes and sizes chosen for the electrodes.For example, the electrodes can be ring-shaped or can be segmentedelectrodes that do not extend 360° about the microstimulator body.

Furthermore, each electrode may be selectively powered as an anode orcathode. For example, a microstimulator can have any combination ofcathodes and anodes (as long as there is at least one cathode and atleast one anode) thereby providing different shaped current fields.Alternatively, a microstimulator can be programmed such that only onepair of electrodes is active at any given time, limited to either a toppair of electrodes or a bottom pair of electrodes. Further, theelectrodes can be sufficiently spaced apart to allow independent currentsettings for each of the electrodes of the microstimulator. In certainembodiments, electrodes are positioned on the two widest portions of amicrostimulator have a top surface and a bottom surface. The electrodeson the bottom surface will be facing towards the fascia and tibial nerveand the electrodes on the top surface will be facing towards the skinand cutaneous saphenous branches. In certain embodiments, amicrostimulator can include an Application Specific Integrated Circuit(ASIC) to provide current steering.

In certain embodiments, a microstimulator has two electrodes in totallocated on the bottom surface of the microstimulator body. In otherembodiments, the microstimulator has four electrodes in total,electrodes positioned on each of the top and bottom surfaces. In oneembodiment, each stimulation pulse is either between an anode andcathode on the top surface or an anode and cathode on the bottomsurface. In another embodiment, each stimulation pulse can use two ormore of these four electrodes with at least one configured as an anodeand one as a cathode.

Such steps of controlling the direction and shape of the electricalsignal applied to the target nerve can be performed after implantationof the microstimulator.

Microstimulators as disclosed herein can be part of a system including aremote pulse generator (not shown) that is in electrical communicationwith an electrode of the microstimulator and is configured to produceone or more electrical signals. Alternatively, microstimulators cancomprise an integral pulse generator. In addition, microstimulators caninclude an integral battery that is rechargeable by inductive couplingor can be part of a system that includes a remote battery operablycoupled to the microstimulator. In other words, a microstimulator may bepowered by bringing a power source external to the mammal's body intocontact with the mammal's skin or may include an integral power source.As such, a pulse generator or battery may be positioned in any suitablelocation, such as adjacent to the microstimulator (e.g., implantedadjacent to the microstimulator), integral with the microstimulator, orat a remote site in or on the patient's body.

In some instances, the microstimulator can include its own power source,e.g., which is capable of obtaining sufficient power for operation fromsurrounding tissues in the mammal's body. Internal power sources canobtain sufficient energy, for example, from muscle movements and othersource of body energy generation that can be harnessed via a capacitoror a balloon device that harnesses the energy, for example, so that aninternal battery is not needed.

Microstimulators can be pre-programmed with desired stimulationparameters. Stimulation parameters can be controllable so that anelectrical signal may be remotely modulated to desired settings withoutremoval of the microstimulator from the target implant site. Remotecontrol may be performed, e.g., using conventional telemetry with animplanted pulse generator and battery, an implanted radiofrequencyreceiver coupled to an external transmitter, and the like. In someinstances, some or all parameters of the microstimulator may becontrollable by the subject, e.g., without supervision by a physician.In other instances, some or all parameters of the microstimulator may beautomatically controllable by a programmer or controller. A controllercan be embodied as software on a multi-purpose external device, such as,for example, a PC, a cell phone, a PDA type device, or tablet.

Certain embodiments as disclosed herein include closed-loop systems. Forexample, a wearable ankle strap or a physician programmer can have aplug-in sensor to sense EMG activity, sense ENG activity, or measuretrigeminal somatosensory evoked potentials (TSEPs), evoked muscle actionpotentials (EMAPs) or electrically evoked compound action potentials(ECAPs) to determine the minimal threshold of stimulation needed toachieve a therapeutic effect. Identifying the minimal threshold neededfor stimulation avoids or minimizes pain for the patient. Such a featurecould also be used for troubleshooting, programming, patient feedbacketc. Other art stimulates at the highest tolerable level, since they areopen loop, with the understanding that such stimulation will result inthe highest probability of being efficacious. Also, other art relies onphysiological responses such as toe twitches or painful musclecontraction to evaluate the programming settings.

Because a microstimulator according to certain embodiments of thepresent disclosure is implanted at a site that is above deep fascia, themicrostimulator is further away from the target nerve. As such, thevariability of distance from such an implant site to the target nervecan be much greater compared to SNS and PTNS both from patient topatient and within a given patient given fluctuations in weight or fluidretention. Such variable distance to the target nerve can undesirablyincrease the requisite size of a microstimulator. To address such aconcern, microstimulators as disclosed herein can have a flat orcylindrical, elongated, low profile configuration. The majority of themicrostimulator can be fabricated from or coated with a material so thatthe microstimulator is “body compliant” and has mechanical propertiessimilar to the tissue at the target implant site. Exemplary materialsinclude polymeric materials with elastic properties or thermal plasticscomprising urethane, aromatic polyurethane, silicones, polyethers,polycarbonates, polytetrafluoroethylene, elastane, or combinationsthereof.

Referring to FIG. 6, in an embodiment, a microstimulator 30 comprises amicrostimulator body 31 having a top surface 32, a bottom surface 34, aproximal end 36 and a distal end 38. Microstimulator body 31 can includean enclosure 33 comprising electrical circuitry that is in electricalcommunication with at least one independently programmable electrode 40(shown as electrodes 40 a, 40 b in FIG. 6) on top surface 32 and/or atleast one independently programmable electrode 42 (shown as electrodes42 a, 42 b in FIG. 6) on bottom surface 34. Although FIG. 6 illustratesthe enclosure at the distal end of the microstimulator body, theenclosure can be located at the proximal end or anywhere between theproximal and distal end. Further, although electrodes 40 and 42 areillustrated as being spaced from enclosure 33, electrodes 40 and 42 canbe disposed on enclosure 33 or other electrodes can be disposed onenclosure 33. The electrical circuitry within enclosure 33 can includemicroprocessors under the control of a suitable software program. Theelectrical circuitry can include other components such as ananalog-to-digital converter, etc.

In certain embodiments, as depicted in FIG. 6, microstimulator body 31comprises two independently programmable electrodes 40 a and 40 b on topsurface 32 that are separated by a distance of at least threemillimeters and two independently programmable electrodes 42 a and 42 bon bottom surface 34 that are similarly separated by a distance of atleast three millimeters.

As stated above, a microstimulator can include one or more re-deployablefixation members to securely anchor the microstimulator at the targetimplant site, which, in certain embodiment, is randomly distributedconnective tissue that is above deep fascia and below the skin. Passiveanchors such as silicone tines that rely on the springiness of thesilicone material to find open space amongst the tissue may notsufficiently fixate a microstimulator to such randomly distributedconnective tissue. Re-deployable fixation members as described hereincan sufficiently fixate the microstimulator to connective tissue andalso can allow the microstimulator to release the connective tissue ifnecessary so that the microstimulator can be re-anchored. In otherwords, if the microstimulator does not stimulate the target nerve or ifthe fixation is not adequate, the re-deployable fixation members can bewithdrawn proximally and released from tissue, the microstimulator canbe re-located, and the fixation members can be re-deployed distallyand/or laterally.

Such re-deployable fixation members can be disposed on the top, bottomor lateral surfaces of the microstimulator body and there can be asingle or multiple re-deployable fixation members disposed on themicrostimulator body. In a preferred embodiment, re-deployable fixationmembers are disposed on the lateral sides of the microstimulator body asillustrated in FIGS. 8 and 9 described in more detail below. Such aconfiguration can ensure that the electrodes of the microstimulator arecorrectly oriented towards the target nerve and that the fixationmembers are urged outward (lateral deployment) in a plane that issubstantially parallel to the field of deep fascia. Also there-deployable fixation members can include tissue interfacing componentssuch as, for example, tines, barbs, teeth, or pincers to provideredundant fixation to ensure successful positioning and anchoring inconnective tissue of the anatomical region. In embodiments, where thefixation members are anchored to tissue above deep fascia and below theskin, the fixation members can be fabricated and configured to lackcertain mechanical properties (e.g. shape, tensile strength,cross-section, aspect ratio, etc.) necessary to pierce deep fascia.

Referring to FIGS. 7 and 8, in an embodiment, microstimulator 30comprises stimulator body 42 having re-deployable fixation member (showngenerally at 44 in FIG. 7) attached thereto. Although FIG. 8 depicts twofixation members 44A and 44B, the microstimulator 30 can include asingle fixation member or more than two fixation members. Each fixationmember 44 can be a clip including two flexible arms 50 (shown asflexible arms 50 a, 50 b, 50 c, and 50 d in FIG. 7) separated by clipbase 52 (shown as clip base 52 a and 52 b in FIG. 7) that definesreceiving space 54. Although arms 50 of fixation member 44 areillustrated as being disposed substantially perpendicular to thelongitudinal axis X of microstimulator body 42, the fixation member canbe attached to the microstimulator body such that the arms extend in aplane substantially perpendicular to the longitudinal axis X of themicrostimulator body.

As illustrated in FIG. 7, delivery tool 56 can be inserted intoreceiving space 54 of fixation member 44 to engage clip base 52. Oncereaching an anatomical site, delivery tool 56 can be rotated to splayopen arms 50. Referring to FIG. 8, to anchor microstimulator 30 into theconnective tissue at the implant site, delivery tool 56 can be rotatedin the opposite direction to urge the tips 58 of arms 50 togetherthereby grabbing and pinching the surrounding connective tissue andaffixing microstimulator to the target implant site. If microstimulator30 needs to be re-anchored, delivery tool 56 can be rotated back againto splay open arms 50 to release the connective tissue and fixationmember 44 can be redeployed at a different implant site. Themicrostimulator can be anchored to an implant site substantiallyparallel to the target nerve or substantially perpendicular to thetarget nerve. In embodiments where the microstimulator is fabricatedfrom a body compliant material, the microstimulator can be compressed inan upward or outward direction when the delivery tool is rotatedproviding additional closing pressure on the fixation member. The tipsof the arms of the fixation member can comprise one or more tines forgrabbing and pinching connective tissue and the angle between multipletines can range from between about 0 to about 90 degrees. Havingmultiple locations where the microstimulator is fixated to surroundingconnective tissue via multiple fixation members or multiple tines at atip of the fixation member increases the surface area of themicrostimulator that is in contact with the connective tissue andprovides strain relief from forces acting to dislodge themicrostimulator.

Referring to FIGS. 9 and 10, in another embodiment, microstimulator 60comprises a microstimulator body 62 having side 66 and re-deployablefixation member 64 slidably attached to side 66. FIG. 9 depictsmicrostimulator 60 having first side 66 a and second side 66 b and twofixation members 64A and 64B attached respectively to first and secondsides 66 a and 66 b of microstimulator body 62. However, themicrostimulator can include a single fixation member or more than twofixation members. In this embodiment, fixation member 64 assumes acoiled configuration in a deployed state, as illustrated in FIG. 10, anda substantially linear configuration in a non-deployed state, asillustrated in FIG. 9. The fixation members can be fabricated from amaterial that allows such a change in configuration. For example, thefixation member can be fabricated from a super-elastic material,polymeric materials, silicone based materials or combinations thereof.The outer surface of the fixation member can include jagged barbed edges74 as illustrated in FIG. 10 to increase the holding force of thefixation member. Additionally, the body of the fixation member caninclude features, such as holes, which allow tissue ingress to increasethe holding force of the fixation member.

A delivery tool can releasably engage the fixation member to urge thefixation member distally or to retract the fixation member proximally.For example, fixation members 64A and 64B can include apertures that aresized and configured to receive a projection disposed on the deliverytool in order to releasably couple the delivery tool to the fixationmember. When loaded into a delivery tool, fixation members 64A and 64Bassume a substantially linear configuration against respective sides 66a and 66 b of microstimulator body 62 as illustrated in FIG. 9. Whenreaching the anatomical site, the delivery tool can urge the fixationmembers 64A and 64B distally through slots 67 a and 67 b, for example,defined by respective first and second side 66 a and 66 b ofmicrostimulator body 62. Fixation members 64A and 64B return to theiroriginal coiled shape as illustrated in FIG. 10 capturing connectivetissue within the space 70 (shown as spaces 70 a and 70 b in FIG. 10)defined by the interior surface 72 (shown as coiled surfaces 72 a and 72b in FIG. 10) of the coiled portion of the fixation members 64A and 64B.The interior diameter of the coiled portion of the fixation member canbe increased or decreased to optimize captured tissue volume. Ifmicrostimulator 60 needs to be re-anchored, the delivery tool canretract fixation members 64A and 64B back through slots 67 a and 67 b torelease the connective tissue and fixation member 64 can be re-deployedinto connective tissue at a different location.

Although the above embodiments describe re-deployable fixation members,other types of fixation members can be used such as deployable, passiveor dissolvable fixation members. In an embodiment, a fixation member cancomprise a reservoir for a deployable biocompatible liquid polymer. Sucha reservoir can be located on the delivery tool or the microstimulatoritself and can contain the biocompatible polymer in a liquid phase. Sucha polymer can have tissue adherent properties that facilitate fixationof the microstimulator to surrounding connective tissue. Further, such aliquid polymer can have properties such that when deployed from itsreservoir it is in the liquid phase, for example, and as time progressesafter deployment, it can increase fixation of the microstimulator toadjacent tissue by forming a semi-solid or solid membrane between themicrostimulator and surrounding connective tissue.

In embodiments where microstimulator is implanted above deep fascia,microstimulators can include features to facilitate tunneling throughskin to an implant site without penetrating deep fascia. For example,the distal end of the microstimulator can be blunt, round, wedge-shaped,asymmetrical, or trowel shaped. Further, the distal end of themicrostimulator can be fabricated from an elastomeric material, such assilicone for example, so that the tip does not pierce deep fascia andconforms to the space within tissue of the anatomical region. Referringto FIG. 11, in an embodiment, microstimulator 80 comprisesmicrostimulator body 82 having a wedge-shaped distal tip 84. Such a tipconfiguration prevents the microstimulator from puncturing deep fasciaand also helps guide the microstimulator to the implant site. The distaltip can comprise rigid structure 86 encased by elastomeric overmold 88.Non-limiting examples of elastomeric materials include silicone andthermoplastic polyurethane. In other embodiments, the distal end isblunt but does not have an elastomeric casing. Referring to FIG. 12, inother embodiments, microstimulator 81 comprises a microstimulator body83 having an asymmetrical, “toboggan-shaped” distal tip 85. In such anembodiment, the distal most point of the tip can be off center from thelongitudinal axis of the microstimulator.

A delivery tool used to implant a microstimulator can also includefeatures to facilitate tunneling through skin to an implant site withoutpenetrating deep fascia and to also evaluate whether the microstimulatoris sufficiently anchored to the implant site thereby indicating that thefixation member is sufficiently anchored to connective tissue of theanatomical region. Referring to FIG. 13, a delivery tool 90 can have adeflectable “ski like” tip 92 that provides for blunt dissection ofsubdermal tissue prior to reaching deep fascia to avoid penetration ofdeep fascia. With respect to evaluating anchoring strength, tip 92 candeflect only when a certain amount of axial force has been reached. Forexample, tip 92 can have a forward deflection force calibrated to thedesired anchoring holding force of a fixation member of amicrostimulator.

Microstimulators and delivery tools can also include features that allowa clinician to detect deep fascia as the microstimulator is insertedinto tissue in embodiments where the implant site is above deep fasciaand below the skin. Such features include mechanical or electricalsensors. For example, referring to FIG. 14, a delivery tool 101 caninclude sensing electrodes 103 and stimulation electrodes 105 to providefor real-time monitoring of impedance between electrode pairs. Thestimulation electrodes 105 of the microstimulator 107 can also be usedas stimulation sources for impedance measurements by exposing tissueoutside delivery tool 101. Typical fascia tissue has a lower impedancethan adipose tissue that is above deep fascia. Therefore, a cliniciancan detect when the electrodes are in contact with fascia. In otherwords, while the delivery tool is advanced along the tissue to animplant site, impedance can be monitored to provide feedback so that thedelivery tool maintains contact with the tissue along the surgicalpathway but does not penetrate into deep fascia. Such feedback can beprovided to the clinician during insertion to detect the deep fascia, toensure that the delivery tool reaches the interface between tissue abovedeep fascia and the deep fascia layer, and allow for a change ofinsertion angle to prevent puncture of deep fascia. Further, duringadvancement of the delivery tool and microstimulator, real timemonitoring is possible to ensure continued contact with tissue above thedeep fascia. Impedance monitoring electrodes can also be used forstimulation and/or sensing during implant procedures for locating ordetecting the target nerve or for target nerve capture confirmationtesting to determine the target implant site.

Microstimulators and delivery tools can also include features that allowa clinician to both detect deep fascia as the microstimulator isinserted into connective tissue as well as determine whether themicrostimulator is sufficiently anchored in the connective tissue site.For example, with reference to FIG. 15, a delivery tool 400 can includea two spring system with one spring system for sensing fascia and theother spring system for verifying anchoring force. Regarding sensingfascia, when the microstimulator (not shown) is inserted and touches thestiffer layer of deep fascia it faces higher resistance and the reactionforce will overrun the stiffness of spring 402 and compresses spring402. As a result, fascia indicator 406 will appear in indicator window410. Regarding anchoring force, after deployment of a fixation member ofthe microstimulator, a pull on handle 412 will apply a tag force on thedistal end of the microstimulator. If the anchoring force is adequate,anchoring indicator 408 will stay in place while indicator window 410moves proximally with handle 412. Anchoring indicator 408 will be viewedthrough indicator window 410. If the anchoring force is not adequate,such force will not be able to keep anchoring indicator 408 in placethus anchoring indicator 308 will move with handle 412 as well and thuswill not appear in indicator window 410. Other methods of confirminganchoring integrity include the use of a Hall sensor with a spring.

As described above, a delivery tool can include stimulation and/orsensing electrodes to provide an electrical signal during the implantprocedure, while monitoring for sensed nerve activation, such as EMG orENG signals, for example. Nerve activation can be monitored in otherways as well. The stimulation or sensing electrodes can be on multiplesides of the delivery tool to allow for stimulation and nerve capturesensing of more than one nerve. By exposing electrodes on themicrostimulator to the external tissue, the microstimulator electrodescan also be used for stimulation or sensing. Further, one electrode ofan array of electrodes on the microstimulator or delivery tool can beused to provide a stimulation signal while the other electrodes can beused to sense resulting nerve activation signals such as EMG or ENGsignals, for example. In addition, sensing can be done from externalelectrodes placed on the skin, such as EMG or ENG electrodes. Thedelivery tool can include visual feedback indications relating to targetnerve activation such as LED indicators. Such localization features thatare utilized while the delivery tool is advanced provide feedback fortarget microstimulator placement adjacent a target nerve. Further,multiple feedback signals can be obtained if targeting more than onenerve.

Regarding determining a target implant site such that the target nerveis localized and the target nerve is captured, as an example,stimulation electrodes of a delivery tool or a microstimulator candeliver an electrical stimulation signal of a certain waveform. Examplestimulation waveforms are shown in FIG. 16, and include a single pulse(shown in example A), a bipulse (shown in example B), an alternatingbipulse (shown in example C), a sweep (shown in example D), a burst(shown in example E), or the like. A pulse in each waveform can befollowed by a predetermined duration during which charge is recapturedfrom the anatomical site. This charge recapture can be achieved in apassive mode or an active mode for example, by reversing the polarity ofthe stimulating electrodes for a predetermined duration. Application ofthe electrical signal can be followed by a detection window of apre-defined time. The detection window can occur concurrently with thecharge recapture. During the detection window, sensing electrode of thedelivery tool, microstimulator, or on the surface of the patient's skin,can detect an EMG signal. When the electrical signal stimulates thetarget nerve (including the tibial nerve or saphenous nerve, forexample), an EMG signal will be generated. Example localization methodsfor each type of waveform are shown in FIGS. 17-21.

A target implant site can be determined, for example, using the systemof FIG. 23. An example microstimulator is shown in the block labeledMICROSTIMULATOR. The sensing electrodes are labeled SENSOR(S). The blocklabeled OUTPUT can provide tactile feedback, visual feedback, and/oraudio feedback of the proximity of the MICROSTIMULATOR to the targetnerve (in other words, whether the target nerve is captured). The OUTPUTcan provide any other kind of feedback, including mechanical feedback inthe form of pressure or vibratory energy transmitted to the operator byan appropriate transducer. However, the feedback can be implemented indifferent/alternative ways.

A stimulation pattern of a predetermined amplitude (Siga) can deliveredby the MICROSTIMULATOR. Sensing can be started simultaneously at theSENSOR(S), yielding a measured signal (Sigb). Siga and Sigb can besimultaneously compared to each other statistically and/ormathematically using signal processing techniques to capture relevantinformation from both signals. When a mathematical cross-correlation ofSiga and Sigb yields a significant cross-correlation Ca-b such thatcorrelation Ca-b exceeds a predetermined value, capture of the targetnerve can be determined to have occurred. In some examples, once capturehas occurred, the audio speaker can start emitting an audible sound tothe operator, and/or the LED can indicate a visual signal to theoperator, and/or the mechanical transducer can transmit a mechanicalTactile signal to the operator. The magnitude of the output fromspeakers, LED, and Tactile can be modulated proportional to thecross-correlation Ca-b, to indicate increasing or decreasing proximityof the MICROSTIMULATOR to the target nerve.

Various examples of stimulation waveforms that can be applied by themicrostimulator or delivery tool and methods of using these stimulationwaveforms to determine a target implant site are described below. Asshown in FIG. 16A, a single pulse stimulus waveform can be generated ata given amplitude, pulse width, frequency, and interphase delay and canbe delivered by an electrode included with the delivery tool or themicrostimulator. A detection window of time can follow after applicationof each pulse of the single pulse stimulus waveform. During thedetection window, sensors can monitor for the EMG signal resulting fromthe stimulation. Referring to FIG. 17, in an embodiment of a method(500) of determining a target implant site, a single pulse stimuluswaveform can be generated (step 501) and can be delivered by anelectrode. The first detection of the EMG can be set as the baseline EMG(including, for example, the strength, power, and/or root mean square(RMS) value) (steps 502-503). Thereafter, EMG activity can continue tobe detected (step 502), and on re-detection, method (500) can comprisereduction of the amplitude of the single pulse stimulus waveform onincrease of the EMG from baseline (step 505). For example, the amplitudecan be reduced by 10%. Method (500) then can comprise continueddetection for a stimulation evoked EMG (step 502). If an EMG is stillelicited by the lower amplitude signal (a decrease is expected based onthe reduced stimulation amplitude), this EMG can be stored as a newbaseline value (including, for example, the strength, power, and/or RMSvalue) (step 503). If the EMG is no longer detected or decreases fromthe baseline, the stimulation can be restored to the previous amplitude,and an error/overshoot condition can be indicated to the user (step506). However, if the EMG remains constant for a time period (e.g.,three seconds or more), the delivery tool can be determined to be at atarget implant site (step 507).

As shown in FIG. 16B, a bipulse stimulus waveform can be generated andcan be delivered by an electrode included with the delivery tool 5 ormicrostimulator 10. Referring to FIG. 18, in an embodiment of a method(600) of determining a target implant site, a bipulse stimulus waveformcan be generated (step 601) and can be delivered by an electrode. Thebipulse stimulus waveform can be a repetition of a pulse pair. Thebipulse stimulation can have a single frequency for the paired pulses.The first pulse in the pair can have a first amplitude (Ampa) and thesecond pulse in the pair can have a second amplitude (Ampb). The secondamplitude can be less than the first amplitude for example by 25%. Adetection window of a predetermined duration can follow afterapplication of every pulse (step 602). During the detection period, afirst EMG corresponding to the first pulse (EMGa) and a second EMGcorresponding to the second pulse (EMGb) can be detected. The firstdetection of the first EMG (EMGa) can be set as the baseline EMG(including, for example, the strength, power, and/or RMS value) (step603). Thereafter, method (600) can comprise continuation of detection ofa stimulation evoked first EMG (EMGa) (step 607) and initiatingdetection for a second EMG (EMGb) (step 604). When a second EMG (EMGb)is detected, the amplitude of the first (Ampa) and second pulse (Ampb)can be decreased (step 605). For example, the amplitude of the firstpulse can be reduced by 10% for example and the amplitude of the secondpulse can be reduced by 5% for example. The sensors can again monitorfor resulting EMGs (steps 604 and 607). If a first EMG (EMGa) is stillelicited by the lower amplitude signal (a decrease is expected based onthe reduced stimulation amplitude), this EMG can be stored as a newbaseline value (including, for example, the strength, power, and/or RMSvalue) (step 603). If EMG due to stimulation (EMGa or EMGb) is no longerdetected, the stimulation amplitudes for both pulses can be restored tothe previous amplitude, and an error/overshoot can be indicated (step608). If at any time the amplitude of the first pulse is less than theamplitude of the second pulse in the pulse pair, the amplitude of thefirst pulse can be set equal to the amplitude of the second pulse (step606). If the second EMG remains constant for a time period (e.g., threeseconds), the delivery tool can be determined to be at a target implantsite (steps 609-610).

As shown in FIG. 16C, an alternating bipulse stimulus waveform can begenerated and can be delivered by an electrode included with thedelivery tool or microstimulator. Referring to FIG. 19, in an embodimentof a method (700) of determining a target implant site, an alternatingbipulse stimulus waveform can be generated (step 701) and can bedelivered by an electrode. The alternating bipulse stimulus waveform canbe a repetition of a pulse pair. Every pulse pair can be delivered at apolarity that is opposite to that of the preceding pulse pair. Thealternating bipulse stimulation can have a single frequency for thepaired pulse. Furthermore, in method (700), each paired pulse cancomprise a first pulse with a first amplitude (cathodic: cAmpa, anodic:aAmpa) and, a second pulse with a second amplitude (cathodic: cAmpb,anodic: aAmpb). The second pulse amplitude in a pulse pair, can be lessthan the first amplitude for example by 25%. The electrical polarity ofevery pair of pulses can be reversed. For example, the pulses can bepaired so that the first amplitude and the second amplitude are bothcathodic, and then the next pair of the first amplitude and the secondamplitude are both anodic to achieve an inversion.

A detection window of a predetermined duration can follow afterapplication of each pulse of an alternating bipulse stimulus waveform.During the detection period, a first cathodic EMG corresponding to thefirst cathodic pulse (cEMGa), a second cathodic EMG corresponding to thesecond cathodic pulse (cEMGb), a first anodic EMG corresponding to thefirst anodic pulse (aEMGa), and a second anodic EMG corresponding to thesecond anodic pulse (aEMGb) can be detected. The first detection of thesecond cathodic EMG (cEMGb) can be set as the baseline EMG (including,for example, the strength, power, and/or RMS value) (step 702-703).Subsequently, after the initial determination of the baseline, method(700) can comprise continued monitoring of second cathodic stimulationpulsed evoked muscle EMG (cEMGb), (step 704). On continued detectionsecond cathodic EMG (cEMGb), (step 704), the subsequent pulses in thealternating bipulse waveform can be generated with a reduced amplitude(step 705). For example, the amplitude of the first anodic and cathodicpulses (cAmpa, aAmpa) can be reduced by 10%, and the amplitude of thesecond anodic and cathodic pulses (cAmpb, aAmpb) can be reduced by 5%.The sensors can again monitor for resulting EMGs, (step 704). If asecond EMG is still elicited by the lower amplitude signal (a decreaseis expected based on the reduced stimulation amplitude), this EMG can bestored as a new baseline value (including, for example, the strength,power, and/or RMS value), (steps 703 and 707). Method (700) can furthercomprise, if an already detected EMG is no longer detected or decreasesfrom the baseline, restoring stimulation to the previous amplitude, andan error/overshoot condition can be indicated, (steps 704, 707, and708). At any time, if the amplitude of the first EMG, (cAmpa, aAmpa) isless than the amplitude of the second EMG, (cAmpb, aAmpb), the amplitudeof the first pulse can be set equal to the amplitude of the secondpulse, (step 706). If EMG activity is detected on any anodic stimuluspulse, (aEMGa or aEMGb), the delivery tool can be determined to be atarget implant site (step 709 and 710).

As shown in FIG. 16D, a sweep stimulus waveform can be generated and canbe delivered by an electrode included with the delivery tool ormicrostimulator. Referring to FIG. 20, in an embodiment of a method(800) of determining a target implant site, a sweep stimulus waveformcan be generated (step 801) and can be delivered by an electrode. Asweep stimulus waveform can be, for example, a train of pulses generatedat a pre-determined frequency and an increasing amplitude. Each pulsecan be followed by a detection window. The train of pulses can berepeated after a maximum amplitude is reached. There may or may not be apause in between the repetition of the pulse train. This implies twofrequencies—one frequency for the pulse in the pulse train and anotherfor the repetition of the pulse train.

In method (800), when a search algorithm is initiated, for example, atrain of cathodic pulses can be generated. The first pulse can start ata sub-threshold value (e.g., 1 mA) and each subsequent pulse in thetrain can increase by a predetermined amplitude, such as 500 μA forexample, until a maximum amplitude (e.g., 20 mA) is reached. Each pulsecan be followed by a respective detection window. Method (800) cancomprise detection of EMG due to nerve stimulation (steps 802 and 803)such that, if such EMG is detected in any detection window, theremaining pulses in the train can be terminated, the amplitude of thepulse that elicited an EMG can be saved as the maximum amplitude, theminimum amplitude can be set to half of the maximum amplitude forexample, and the waveform can be restarted. If the pulse amplitudereaches a maximum amplitude (20 mA for example), with no detection of anEMG, the train can be reset and restart at the minimum amplitude. If anEMG has been detected and the maximum amplitude remains constant onthree consecutive pulse trains, a target implant site can be indicatedto the operator, (steps 804-805). If an EMG has been detected on aprevious train of pulses, and the maximum amplitude is reached withoutdetecting the EMG, the maximum amplitude can be increased by 500 μA forexample unless the maximum amplitude is 20 mA for example. If themaximum amplitude is 20 mA for example and a detected EMG is notre-detected on three subsequent pulse trains, an Error can be indicated(steps 806-807). If the maximum amplitude is increased twiceconsecutively after having detected an EMG due to nerve stimulation, anOvershoot can be indicated (steps 806-807).

As shown in FIG. 16E, a burst stimulus waveform can be generated and canbe delivered by an electrode included with the delivery tool ormicrostimulator. Referring to FIG. 21, in an embodiment of a method(900) of determining a target implant site, a burst stimulus waveformcan be generated (step 901) and delivered by an electrode. A burststimulus waveform can be, for example, five cathodic or anodic pulses atthe same polarity for a predetermined frequency (e.g., 20 Hz). The pulseburst can be repeated at another frequency (e.g., 2 Hz). As a result,each burst lasts for a time period (e.g., 250 ms) with a delay (e.g.,250 ms) between the last pulse of one burst and the first pulse of thenext burst. The pulses can start at an amplitude (20 mA for example) andeach burst can have an overlapping EMG detection window that can extendbefore the start and beyond the end of each burst, for example 100 msbefore and 100 ms after a burst. The burst frequency and the amplitudecan be chosen to induce tetanic contraction of the muscle (approximatinga 100 ms twitch with a 70 ms relaxation phase, an interpulse delay of 50ms between the supra-threshold pulses should summate to tetany, forexample). Since tetanic, or near tetanic, contraction is expected, theaverage EMG signal can be compared to the baseline EMG to detect fortetanic recruitment. Expanding the EMG detection before the start of theburst can allow the baseline EMG to be noted and a stimulation EMG to bedistinguished from an underlying EMG tone.

Method (900) further comprises continuous detection of EMG due to nervestimulation, (step 902). When an EMG due to tetanic stimulation isdetected, or an increase in EMG signal is detected, the amplitude of thepulses can be decreased by 10% for example and the EMG level noted,(steps 903 and 905). If the EMG due to nerve stimulation remainsconstant on multiple consecutive bursts, for example four or moreconsecutive bursts, a target implant site can be indicated to theoperator, (steps 904 and 907). If the EMG due to nerve stimulationdecreases on multiple consecutive bursts, for example two or moreconsecutive bursts, an Error and/or Overshoot can be indicated to theoperator, (steps 904 and 906).

FIGS. 23-30 are schematic illustrations of an insertion tool 300 anddepict various stages of deployment of an embodiment of amicrostimulator 400. With reference to FIG. 23, insertion tool 300includes a handle 311 comprising a handle body 312. Extending fromhandle body 312 is a sheath 309 having a tip for fascia detection and/orprotection 301. Such a tip can include any of the features describedabove for detecting deep fascia and avoiding puncturing deep fascia.Handle body 312 also includes a slider for anchor deployment 302, ananchor sensor lock 304, an anchor feedback sensor 306, a slider 308 forsheath 309, a slider for microstimulator release 310, and amicrostimulator release lock 314. Optical guidance systems ortechnology, such as Optical Spectroscopy, Optical Coherence Tomographyor Optical Fiber Probes, can also be used to identify when the deliverytool has reached the deep fascia in embodiments where the implant siteis above deep fascia. As part of a system, one or more biocompatible,mechanically robust, optical fibers with less than approximately one mmcross-section, high aspect ratios in excess of 100:1 can be effectivelyintegrated with the delivery tool. Optical spectroscopy techniquesexploit the fact that different biological tissue types arecharacterized by different absorption/reflection spectra, depending ontheir physical composition. In other words, skin, fascia, fat, muscle,and ligaments include different types, sizes, shapes and orientation ofcells, providing distinctly different optical properties, e.g.refractive index and absorption coefficients, which can be used fortissue identification at the tip of the delivery tool and closed-loopguidance of the tip to the deep fascia. Similarly, Optical CoherenceTomography is another embodiment of an optical guidance technique thatcan be used to detect if the delivery tool has reached the deep fascia.The Fourier domain of this technique uses optical fibers and lowcoherence interferometry to produce two-dimensional images of a fewmicrometers in axial resolutions at a high rate, enabling real-timefeedback to the physician during the procedure. Another embodiment canutilize a fiber Bragg grating, a type of distributed Bragg reflector,constructed in a short segment of one or more optical fibers thatreflects particular wavelengths of light and transmits all others. Thefiber Bragg grating strain sensor can act as a pressure gauge thatdiscriminates between different types of tissue along the (tunnel to theimplant site) thus providing continuous and real time measurements ofthe pressure experienced by the delivery tool tip during itsadvancement. The deep fascia can be localized by detecting the abruptdeflection of the fiber and resulting Bragg wavelength shift due to thepassage from a soft adipose tissue region to the thin and strong “hard”deep fascia tissue. During the procedure, a delivery tool system canmonitor the Bragg wavelength shift as a function of time in response tothe different degree of elasticity and consistency of the tissue beingpenetrated thereby making it possible to distinguish the tissue boundaryat the deep fascia from the other boundaries.

The structure of the insertion tool 300—which is an apparatus fordelivering an electrical microstimulator—will now be discussed in moredetail, with specific reference to FIGS. 32-38 and the embodiment of theinsertion tool 300 shown therein.

As depicted in FIGS. 32-34, the insertion tool 300 includes a handle 311having proximal and distal handle ends 1106 and 1108, respectively,longitudinally separated by a handle body 312. The term “longitudinally”is used herein to indicate a direction parallel to arrow “L-L” in FIG.32. The distal handle end 1108 may include a rod aperture 1110.

An elongate delivery rod 1100 includes a delivery sheath (a.k.a. sheath309) for reciprocal movement with respect to the handle body 312. Thedelivery rod 1100 extends longitudinally from the handle body 312 andhas proximal and distal rod ends 1112 and 1114, respectively,longitudinally separated by a rod body 1116. The delivery sheath 309 iscapable of reciprocal movement at least partially between the proximaland distal rod ends 1112 and 1114. At least a portion of the rod body1116 may extend longitudinally through the rod aperture 1110 to placethe delivery rod 1100, or portions thereof, in mechanical contact withstructures at least partially enclosed inside the handle body 312.

The distal rod end 1114 may be at least one of flexible, deflectable andblunt such that the delivery rod 1100 is deflected by a deep fascialayer to remain above the deep fascia layer, during use of the insertiontool 300. A patient tissue sensor may be associated with the deliveryrod 1100 (and/or with the tip for fascia detection and/or protection301), and thus may communicate to a user, in any desired manner, format,or the like, information about a patient tissue adjacent to the distalrod end 1114. The information from the patient tissue sensor may assistwith maintaining the delivery rod 1100 above the deep fascia layer, forexample.

A microstimulator docking feature 1102 associated with the delivery rod1100 is provided for selectively maintaining the electricalmicrostimulator 400 on the delivery rod 1100, such as at the distal rodend 1114. The microstimulator docking feature 1102 includes at least onearm 1104 (two shown; each may be similar to inner shaft 322) whichselectively engages the electrical microstimulator 400, such as underthe influence of an arm-urging force applied by the delivery sheath 309.It is contemplated that the plurality of arms 1104 will splay laterallyinward and outward with respect to the microstimulator 400,respectively, as the delivery sheath 309 moves toward and away from thedistal rod end. (That is, as the delivery sheath 309 of the delivery rod1100 moves distally and proximally with respect to the handle body 312).

The motion of the arms 1104 laterally inward and outward due tolongitudinal motion of the delivery sheath 309 can be thought of assimilar to the working of a “mechanic's claw” grabber tool. That is, thearms 1104 are configured to splay outward, such as in the configurationof FIG. 36, when in a “resting” state. The delivery sheath 309 is thendrawn distally around the arms 1104, such as in FIG. 37, to “bundle” andurge a more proximal portion of each arm 1104 laterally inward, which,in turn, causes the cantilevered distal ends of the arms 1104 to moveinwardly, as well. The delivery sheath 309 is moved distally to apredetermined location which causes the arms 1104 to exert a desiredinward force upon the electrical microstimulator 400 and thus maintainit in position at the distal rod end 1114.

As shown in FIG. 38, at least one arm 1104 may include a distal arm endengager 1118 for selective engagement with a corresponding dockingfeature 1120 of the electrical microstimulator 400. For example, and asshown in the Figures, the distal arm end engager 1118 is a stub whichfits into a corresponding aperture serving as the docking feature 1120,to fit together in a male/female manner and thus “hitch” the electricalmicrostimulator 400 to the delivery rod 1100 as long as the distal armend engager 1118 and docking feature 1120 are engaged. It iscontemplated that the male/female features of the distal arm end engager1118 and docking feature 1120 could be reversed, and/or that the distalarm end engager 1118 and docking feature 1120 could selectively engagemagnetically, electromagnetically, via an interference fit, throughanother mechanical structure, or in any other desired manner. Forexample, the arms 1104 could include, or at least partially be replacedby, a “hoop” or a “sleeve” type slotted structure which rotates relativeto the docking feature 1120 for a “bayonet” or “quarter-turn” typeengagement of the electrical microstimulator 400.

An anchor test may be associated with the handle body 312. The anchortester selectively senses motion of an electrical microstimulator 400 atleast partially engaged with the microstimulator docking feature 1102,under influence of an applied predetermined longitudinal testing force.The sensed motion of the electrical microstimulator 400 may be sensedentirely mechanically. For example, once the arms 403 a and 403 b of theelectrical microstimulator have been released to engage the patienttissue but the electrical microstimulator 400 is still “docked” at thedistal rod end 1114, the user could pull back slightly on the insertiontool 300 by tugging on the handle 311, and then could manually assessthe anchoring force of the electrical microstimulator 400 into thepatient tissue by “feel”. That is, the user could decide whether theresistance posed by the electrical microstimulator 400 to thepredetermined longitudinal testing force of the user's pulling handwould seem to indicate an acceptable anchoring of the electricalmicrostimulator 400 into the patient tissue. This “manual” testing is anexample of an entirely manual anchor tester which is associated with thehandle body 312 via the user's hand.

Another example of an anchor tester is shown particularly in FIGS. 39-40and numbered 1122. It should be noted that distance AM in FIGS. 39 and40 remains constant during anchor testing, since that distance isassociated with structures of the anchor tester 1122 which are heldstationary relative to the handle body 312. The “changing position”portions of the anchor tester 1122 are moving relative to distance AM,as shown in FIGS. 39-40.

In the anchor tester 1122 of the Figures—which is located at leastpartially within the handle body 312—sensed motion of the electricalmicrostimulator 400 is sensed at least partially electrically, throughthe use of a proximity sensor 1124 (e.g., a Hall effect sensor). Forexample, and as shown in at least FIG. 35 and the sequence of FIGS.39-40, an anchor sensor lock 304 may be manipulated. Here, the anchorsensor lock 304 includes a cam 1152 which interacts with the handle body312 in a “blocking” or “wedging” manner and thus helps to selectivelychange a longitudinal distance between a block 1126 and a spring anchor1128 which is affixed to the handle body 312. A spring 1130 extendsbetween the block 1126 and the spring anchor 1128. The block is attachedto a proximal end of a shaft 315 which is, in turn, attached to theproximal ends of the arms 1104. Accordingly, longitudinal motion of thearms 1104 will directly translate, through the shaft 315, to the block1126.

In FIG. 39, the cam 1152 of the anchor tester 1122 is “bracing” orurging the block 1126 distally, which causes the spring 1130 to stretchagainst the spring anchor 1128. Then, in FIG. 40, the anchor sensor lock304 has been manipulated to turn the cam 1152 and thus “release” theblock 1126 for a limited amount of longitudinal movement and permittesting of the anchoring force holding the electrical microstimulator400 to the patient tissue. It should be noted that, at the time theanchor sensor lock 304 is turned as in FIG. 40, the arms 1104 are stillengaged with the docking feature 1120 of the electrical microstimulator400, but the sheath 309 has been pulled slightly proximally, to releasethe arms 403 a and 403 b into engagement with the patient tissue.

It is contemplated that spring 1130 could instead be engaged with shaft315 in such a manner as to be in compression while in a resting state.During the force test, when the cam 1152 is rotated as discussed above,block 1126 will be pushed distally, then, to stretch the spring 1130 andthus administer the anchoring force test.

In order to test the anchoring force holding the arms 403 a and 403 b inengagement with the patient tissue, the user holds the handle 311substantially longitudinally stable, and then moves the anchor sensorlock 304 into the “active testing” position shown in FIG. 40. Thisrotates the cam 1152 so that it no longer is urging the block 1126distally. The proximity sensor 1124 detects whether block 1126 movesproximally in that “active testing” position due to the spring 1130force tending to urge the block 1126 toward the spring anchor 1128. Thisdetection by the proximity sensor 1124 may be aided by magnet 1132carried on the block 1126. The spring constant of spring 1130 should bechosen in order to exert a predetermined longitudinal testing force uponthe block 1126, and by extension on the shaft 315, through the arms1104, through the body of the electric microstimulator 400, and finallyto pull on the arms 403 a and 403 b as they are secured into the patienttissue. When the predetermined longitudinal testing force is chosen toreflect a desired anchoring force of the arms 403 a and 403 b into thepatient tissue, the arms 403 a and 403 b will resist contraction ofspring 1130 when the electric microstimulator 400 is anchored as desiredinto the patient tissue. If the arms 403 a and 403 b are indeed anchoredas desired, the block 1126 will remain substantially in the positionshown in FIG. 39, regardless of the rotational position of cam 1152. Forexample, there may be a slight gap between the cam 1152 and the “ledge”of the block 1126 when the arms 403 a and 403 b are resisting the spring1130 force.

In contrast, when the arms 403 a and 403 b are not properly “set” oranchored into the patient tissue and the predetermined longitudinaltesting force is exerted through operation of the anchor tester 1122,the force between the arms 403 a and 403 b and the patient tissue willnot be sufficient to overcome the spring 1130 force, the arms 403 a and403 b will loosen or “let go” from the patient tissue, and the block1126 will be able to move slightly proximally, toward the spring anchor1128. This is the situation shown in FIG. 40. The proximity sensor 1124will pick up that slight movement and indicate to the user, in anydesired manner, that the electric microstimulator 400 is not anchoredinto the patient tissue as desired. The user can then manipulate thesheath 309, or in any other desired manner recapture the fixation member402 and—for example—redeploy the fixation member 402 at the targetimplant site in hopes of achieving a stronger anchoring force. Testingcan be done, via a simple manual “pullback” and/or the anchor tester1122, until the user is either satisfied with the resistance of the arms403 a and 403 b to the predetermined longitudinal testing force, ordeployment of that particular electric microstimulator 400 is aborted.

The anchor tester 1122 may interface with an anchor indicator, such asanchor feedback sensor 306, to communicate to a user sensed motion ofthe electrical microstimulator 400 under the influence of thepredetermined longitudinal testing force. For example, as shown in theFigures, the anchor indicator may convey to a user (e.g., throughgreen/yellow/red lights) the sensed anchoring “tightness” of the arms'403 a and 403 b grip into the patient tissue responsive to input fromthe proximity sensor 1124.

In order to control and manipulate the very structure of the insertiontool 300 as described, the insertion tool 300 may include a userinterface 1134 having a plurality of user-actuated controls toselectively and mechanically manipulate at least one of the deliverysheath 309 and the anchor tester 1122. For example, at least one of theuser-actuated controls may be a slider for reciprocal movement at leastpartially between the proximal and distal handle ends 1106 and 1108.Another example of a suitable user-actuated control may be a sheath lock314 to selectively prevent longitudinal motion of the delivery sheath309 with respect to the handle body 312. The operation of severalsliders, and other components of the user interface 1134 will now bedescribed with reference to FIGS. 24-31, in which one example sequenceof operation of the insertion tool 300 is at least partially depicted.

FIG. 24 illustrates insertion tool 300 during the pre-deployment stageand during the sensing stage. At both these stages, slider for anchordeployment 302 of the user interface 1134 is in a proximal position inhandle body 312, anchor sensor lock 304 is in a locked configuration,slider 308 for sheath 309 is in a distal position in handle body 312,and slider for microstimulator release 310 is locked and in a distalposition in handle body 312. During the sensing stage (that is, whilethe insertion tool 300 is being used to carry the electricmicrostimulator 400 to the target implant site), sensing can beperformed by electrodes of the microstimulator 400 and/or by electrodeson the bottom surface of sheath 309.

FIG. 25 illustrates insertion tool 300 during the anchor deploymentstage. At this stage, the slider for anchor deployment 302 is urgeddistally to deploy a fixation member 402 of the microstimulator. FIG. 26illustrates insertion tool 300 during the anchor release stage. At thisstage, slider 308 for sheath 309 is pulled back proximally to exposemicrostimulator 400 and slider for anchor deployment 302 is urgeddistally to fully deploy fixation member 402. Arms 403 a and 403 b offixation member 402 have a shape memory and/or material elasticityproperty such that they spring outward once sheath 309 is pulled backproximally to expose arms 403 a and 403 b.

FIGS. 27-28 illustrate insertion tool 300 at the anchor confirmationstage, of which FIGS. 39-40 are a partial detail view. At this stage,anchor sensor lock 304 is in an unlocked configuration. Unlocking shaft320 within handle body 312 activates a spring 1130 to place apredetermined longitudinal testing force on fixation member 402 toensure it is properly secured. Feedback received from the anchorfeedback sensor 306 (which can be a Hall effect sensor) can be sent toan external processor via an electrical connector or a separate unitplugged into the insertion tool 300 and then sent back to LEDindicators.

FIGS. 29-30 illustrate insertion tool 300 during the microstimulator 400release stage, in which is presumed that the anchor testing process hasbeen successful in indicating a desired anchoring force of theelectrical microstimulator 400 into the patient tissue. At this stage,slider for microstimulator release 310 is unlocked, as illustrated inFIG. 29, and pulled back proximally, as illustrated in FIG. 30, torelease microstimulator 400. Shaft 315, attached to slider formicrostimulator release 310, is retracted, allowing an inner shaft 322(such as arm 1104) to retract laterally from a feature, such as, forexample, a “trailer hitch” mechanism or other docking feature 1120, onthe microstimulator 400, as previously described. In certainembodiments, prior to finalizing the implant of the microstimulator by“undocking” the microstimulator from the delivery tool and retractingthe delivery tool, the microstimulator can be programmed to deliverstimulation at a predetermined intensity deemed to have therapeuticbenefits as described above. For many patients, the stimulation iseither imperceptible or produces paresthesia. However, some patients mayfind the stimulation to be uncomfortable and/or even painful. Byinquiring about the sensation perceived by the patient before“undocking” the microstimulator from the delivery tool, the probabilityof prescribed therapy compliance is increased and that of any adverseeffects due to stimulation is decreased.

Turning now to FIG. 41, a flowchart depicting an example method ofdelivering an electrical microstimulator 400 to a target implant site ofa patient's body is schematically illustrated. The method includes, atfirst action block 1136, providing a delivery tool 300. The deliverytool 300, which may be similar to the insertion tool 300 shown in FIGS.23-40, includes a handle 311 having a handle body 312. An elongatedelivery rod 1100 includes a delivery sheath 309 for reciprocal movementwith respect to the handle body 312. The delivery rod 1100 extendslongitudinally from the handle body 312. A microstimulator dockingfeature 1102 includes at least one arm 1104. The arm 1104 selectivelyengages and releases the electrical microstimulator 400 under influenceof the delivery sheath 309. An anchor tester 1122 is associated with thehandle body 312. Control then proceeds to second action block 1138,where the electrical microstimulator 400 is engaged with the at leastone arm 1104 of the microstimulator docking feature 1102. In the thirdaction block 1140, then, the delivery sheath 309 is manipulated tomaintain the electrical microstimulator 400 on the delivery rod 1100with the arm 1104. This could be accomplished at least in part, forexample, by manipulating a user-actuated control in mechanicalcommunication with the delivery sheath 309. Proceeding to fourth actionblock 1142, the electrical microstimulator 400, which is maintained onthe delivery rod 1100 by the microstimulator docking feature 1102, iscarried to the target implant site.

With the electrical microstimulator 400 at least partially maintained onthe delivery rod 1100 by the microstimulator docking feature 1102, apredetermined longitudinal testing force is applied to the electricalmicrostimulator 400 via the anchor tester 1122, as shown in fifth actionblock 1144. In sixth action block 1146, motion of the electricalmicrostimulator 400 under influence of the applied predeterminedlongitudinal testing force is sensed to determine anchoring security ofthe electrical microstimulator 400 at the target implant site.

When fifth and sixth action blocks 1144 and 1146 are carried outentirely mechanically, such as at least partially manually by the user,these actions could occur by way of a fairly simple “pullback” scheme,in which the user tugs on the handle 311 and then determines, bysubjective feel, whether the electric microstimulator 400 is anchored asdesired.

In contrast, when fifth and sixth action block 1144 and 1146 are carriedout at least partially electrically, applying a predeterminedlongitudinal testing force to the electrical microstimulator 400 via theanchor tester 1122 may include exposing the electrical microstimulator400 to the predetermined longitudinal testing force produced by atesting spring 1130 within the handle body 312, which is in mechanicalcommunication with the electrical microstimulator 400. (E.g., throughthe previously described linkage between the block 1126, shaft 315, andarms 1104.) Sensing motion of the electrical microstimulator 400 mightthen include at least partially detecting motion of at least a portionof the delivery rod 1100 via a proximity sensor 1124 associated with thetesting spring 1130.

In seventh action block 1148, anchoring security of the electricalmicrostimulator 400 at the target implant site is communicated to a userof the delivery tool 300. This could include, for example, interfacingthe anchor tester 1122 with a user-perceptible anchor indicator 36,and—responsive to sensed motion of the electrical microstimulator 400under the predetermined longitudinal testing force—providing a signal tothe anchor indicator.

Finally, at eighth action block 1150, the electrical microstimulator 400is at least partially released from the delivery rod 1100 at the targetimplant site by manipulating the delivery sheath 309 to release theelectrical microstimulator 400 from the at least one arm 1104 of themicrostimulator docking feature 1102. This could occur, for example, viapulling the delivery sheath 309 proximally to allow the arms 1104 tosplay away from the docking feature 1102 of the electric microstimulator400.

An example of operation of certain force-testing aspects of theinvention can be summarized as follows, regardless of the exact physicalarrangement of the components (though the above described insertion tool300 is referenced for the sake of description):

1. There is a spring 1130 attached to a structure (e.g., arms 1104) thatholds the microstimulator 400. The attachment, and the holding, can bedirect or indirect (for example, through an adapter).

2. The spring 1130 is compressed or tensioned using a cam 1152. For aspring, F=kX, where F is the force, k is the spring constant and X isthe displacement (compression or tension) of the spring 1130. Now thatthe cam 1152 displaces one end of the spring 1130, there is energy(force) stored in the spring 1130 equivalent to K*displacement of thetip.

3. When it is time to perform a force test, the cam 1152 will berotated. Now that the spring 1130 is free it will deliver the force(pushing or pulling) to the structure holding the microstimulator 400.

4. If the microstimulator 400 anchoring force is adequate, the springforce will not be able to displace the structure. If the force is notadequate, the spring 1130 will overpower the structure holding themicrostimulator 400, and that structure will move backward as a result.

5. When the structure moves, a magnet that was connected to thestructure (e.g., block 1126) will move and that will alter the magneticcircuit (flux).

6. The change of the flux will be sensed by the magnetic proximitysensor 1124, and the “failure” of the spring 1130 anchoring test will becommunicated to the user as desired.

Embodiments as disclosed herein are directed to improving pelvic floordysfunction and pain, such as peripheral nerve pain. Pelvic floordysfunction includes bladder dysfunction, bowel dysfunction, and fecalincontinence. Bladder dysfunction includes urinary incontinence such asurge incontinence, mixed incontinence, and overflow incontinence.Bladder dysfunction also includes “voiding dysfunction,” which refers tourinary incontinence, urinary retention conditions, high urinaryfrequency, high or low frequency of voiding, symptoms of bladder/pelvicpressure/pain, detrusor hyperrflexia, and voiding disorders caused bynerve damage, including interstitial cystitis. Overactive bladder is aspecific type of voiding dysfunction that includes any or all of thefollowing symptoms: urinary frequency (bothersome urination eight ormore times a day or two more times at night), urinary urgency (thesudden, strong need to urinate immediately), urge incontinence (leakageor gushing of urine that follows a sudden strong urge) and nocturia(awakening two or more times at night to urinate). Bowel dysfunctionincludes constipation (including idiopathic constipation), fecalincontinence, and problems with fecal movement, voiding and containment.Improving pelvic floor dysfunction can also include modulatingcontraction of the pelvic floor or “pelvic diaphragm.” Over time,therapy may cause contractions that restore the strength of pelvicorgans and muscles, which may be a goal of the therapy. Stimulationinduced modulation of pelvic floor, sphincter or other targets canalleviate or eliminate many symptoms of urinary/fecal disorders

As stated above, embodiments as disclosed herein differ from othermethods of treating pelvic floor dysfunction, such as an overactivebladder. SNS and PTNS involve placing an electrode below deep fascia inclose proximity to the target nerve such as the sacral nerve or thetibial nerve. As such, the electrodes have a greater probability ofrecruiting the respective target nerve and also require less energy toprovide a therapy signal to the target nerve since the electrodes arepositioned close to the target nerve. However, SNS requires invasivesurgery such as dissecting the lumbodorsal fascia and separating theunderlying paravertebral muscles to access the sacral nerve. In PTNS, aneedle electrode is inserted across the cutaneous, superficial and deeptissue into the tibial nerve. Since the needle is not insulated, itstimulates all layers from the dermis down to the tibial nervesimultaneously. Cases have been reported where the intensity of theelectrical signal delivered by the electrode is too high at the needlesite prior to reaching the recommended therapeutic threshold asindicated by a “toe twitch” in the patient. Also, as an in-officeprocedure needed chronically, the personal burden is such that manypatients stop the therapy before achieving the full benefit possible.Transcutaneous tibial nerve stimulation is less invasive than SNS andPTNS but is challenging in its own respect. For example, the variabilityof distance from skin to tibial nerve is much greater than deep fasciato tibial nerve both from patient to patient and within a given patientshould they have fluctuations in their weight or fluid retention. Also,the reusable electrode placement on the skin is subjectively done by thepatient and therefore variable in location and robustness of interface(e.g. hair interferes conduction of stimulation) from session to sessionand patient to patient. In addition, sensory fibers in the skin closestto the transcutaneous electrodes provide a level of discomfort with thestimulation, variable from patient to patient, which could limit thelevel of stimulation to less than a therapeutic level. Embodiments ofdevices and methods as described herein provide a minimally invasive yettargeted and efficacious form of therapy for improving pelvic floordysfunction.

Each of the disclosed aspects and embodiments of the present disclosuremay be considered individually or in combination with other aspects,embodiments, and variations of the disclosure. Unless otherwisespecified, none of the steps of the methods of the present disclosureare confined to any particular order of performance.

While aspects of this disclosure have been particularly shown anddescribed with reference to the example aspects above, it will beunderstood by those of ordinary skill in the art that various additionalaspects may be contemplated. For example, the specific methods describedabove for using the apparatus are merely illustrative; one of ordinaryskill in the art could readily determine any number of tools, sequencesof steps, or other means/options for placing the above-describedapparatus, or components thereof, into positions substantively similarto those shown and described herein. In an effort to maintain clarity inthe Figures, certain ones of duplicative components shown have not beenspecifically numbered, but one of ordinary skill in the art willrealize, based upon the components that were numbered, the elementnumbers which should be associated with the unnumbered components; nodifferentiation between similar components is intended or implied solelyby the presence or absence of an element number in the Figures. Any ofthe described structures and components could be integrally formed as asingle unitary or monolithic piece or made up of separatesub-components, with either of these formations involving any suitablestock or bespoke components and/or any suitable material or combinationsof materials; however, the chosen material(s) should be biocompatiblefor many applications. Any of the described structures and componentscould be disposable or reusable as desired for a particular useenvironment. Any component could be provided with a user-perceptiblemarking to indicate a material, configuration, at least one dimension,or the like pertaining to that component, the user-perceptible markingpotentially aiding a user in selecting one component from an array ofsimilar components for a particular use environment. A “predetermined”status may be determined at any time before the structures beingmanipulated actually reach that status, the “predetermination” beingmade as late as immediately before the structure achieves thepredetermined status. The term “substantially” is used herein toindicate a quality that is largely, but not necessarily wholly, thatwhich is specified—a “substantial” quality admits of the potential forsome relatively minor inclusion of a non-quality item. Though certaincomponents described herein are shown as having specific geometricshapes, all structures of this disclosure may have any suitable shapes,sizes, configurations, relative relationships, cross-sectional areas, orany other physical characteristics as desirable for a particularapplication. Any structures or features described with reference to oneaspect or configuration could be provided, singly or in combination withother structures or features, to any other aspect or configuration, asit would be impractical to describe each of the aspects andconfigurations discussed herein as having all of the options discussedwith respect to all of the other aspects and configurations. A device ormethod incorporating any of these features should be understood to fallunder the scope of this disclosure as determined based upon the claimsbelow and any equivalents thereof.

Other aspects, objects, and advantages can be obtained from a study ofthe drawings, the disclosure, and the appended claims.

We claim:
 1. An apparatus for delivering an electrical microstimulator,the apparatus comprising: a handle having a handle body, an elongatedelivery rod including a delivery sheath for reciprocal movement withrespect to the handle body, the delivery rod extending longitudinallyfrom the handle body; a microstimulator docking feature for selectivelymaintaining the electrical microstimulator on the delivery rod, themicrostimulator docking feature including at least one arm whichselectively engages the electrical microstimulator; and an anchor testerassociated with the handle body for selectively sensing motion of theelectrical microstimulator under influence of an applied predeterminedlongitudinal testing force.
 2. The apparatus of claim 1, including auser interface having a plurality of user-actuated controls toselectively and mechanically manipulate at least a portion of at leastone of the delivery rod and the anchor tester.
 3. The apparatus of claim1, wherein the anchor tester interfaces with an anchor indicator tocommunicate to a user sensed motion of the electrical microstimulatorunder the influence of the predetermined longitudinal testing force. 4.The apparatus of claim 1, wherein the microstimulator docking featureincludes a plurality of arms for splaying laterally inward and outward,respectively, as a delivery sheath of the delivery rod moves distallyand proximally with respect to the handle body.
 5. The apparatus ofclaim 1, including a patient tissue sensor associated with the deliveryrod and communicating to a user information about a patient tissueadjacent to the delivery rod.
 6. A method of delivering an electricalmicrostimulator to a target implant site of a patient's body, the methodcomprising: providing a delivery tool, the delivery tool including ahandle having a handle body, an elongate delivery rod including adelivery sheath for reciprocal movement with respect to the handle body,the delivery rod extending longitudinally from the handle body, amicrostimulator docking feature including at least one arm, the armselectively engaging and releasing the electrical microstimulator underinfluence of the delivery sheath, and an anchor tester associated withthe handle body; engaging the electrical microstimulator with the atleast one arm of the microstimulator docking feature; manipulating thedelivery sheath to maintain the electrical microstimulator on thedelivery rod with the arm; carrying the electrical microstimulator,maintained on the delivery rod by the microstimulator docking feature,to the target implant site; with the electrical microstimulator at leastpartially maintained on the delivery rod by the microstimulator dockingfeature, applying a predetermined longitudinal testing force to theelectrical microstimulator via the anchor tester; sensing motion of theelectrical microstimulator under influence of the applied predeterminedlongitudinal testing force to determine anchoring security of theelectrical microstimulator at the target implant site; communicatinganchoring security of the electrical microstimulator at the targetimplant site to a user of the delivery tool; and at least partiallyreleasing the electrical microstimulator from the delivery rod at thetarget implant site by manipulating the delivery sheath to release theelectrical microstimulator from the at least one arm of themicrostimulator docking feature.
 7. The method of claim 6, whereinmanipulating the delivery sheath includes manipulating a user-actuatedcontrol in mechanical communication with the delivery sheath.
 8. Themethod of claim 6, wherein applying a predetermined longitudinal testingforce to the electrical microstimulator via the anchor tester includesthe user exerting the predetermined longitudinal testing force manuallyto the handle body.
 9. The method of claim 8, wherein sensing motion ofthe electrical microstimulator including the user manually detectingmotion of the handle body under the applied predetermined longitudinaltesting force.
 10. The method of claim 6, wherein applying apredetermined longitudinal testing force to the electricalmicrostimulator via the anchor tester includes exposing the electricalmicrostimulator to the predetermined longitudinal testing force producedby a testing spring within the handle body in mechanical communicationwith the electrical microstimulator.
 11. The method of claim 10, whereinsensing motion of the electrical microstimulator includes at leastpartially detecting motion of at least a portion of the delivery rod viaa proximity sensor associated with the testing spring.
 12. The method ofclaim 6, wherein communicating anchoring security of the electricalmicrostimulator at the target implant site to a user of the deliverytool includes: interfacing the anchor tester with a user-perceptibleanchor indicator; and responsive to sensed motion of the electricalmicrostimulator under the predetermined longitudinal testing force,providing a signal to the anchor indicator.
 13. An apparatus fordelivering an electrical microstimulator, the apparatus comprising: ahandle having proximal and distal handle ends longitudinally separatedby a handle body, the distal handle end including a rod aperture; anelongate delivery rod having proximal and distal rod ends longitudinallyseparated by a rod body and including a delivery sheath for reciprocalmovement at least partially between the proximal and distal rod ends, atleast a portion of the rod body extending longitudinally through the rodaperture; a microstimulator docking feature associated with the deliveryrod, the microstimulator docking feature for selectively maintaining theelectrical microstimulator at the distal rod end, the microstimulatordocking feature including at least one arm which selectively engages theelectrical microstimulator under influence of an arm-urging forceapplied by the delivery sheath; and an anchor tester associated with thehandle body, the anchor tester selectively sensing motion of anelectrical microstimulator at least partially engaged with themicrostimulator docking feature, under influence of an appliedpredetermined longitudinal testing force.
 14. The apparatus of claim 13,including a user interface having a plurality of user-actuated controlsto selectively and mechanically manipulate at least one of the deliverysheath and the anchor tester.
 15. The apparatus of claim 14, wherein atleast one of the user-actuated controls is a slider for reciprocalmovement at least partially between the proximal and distal handle ends.16. The apparatus of claim 13, wherein the anchor tester interfaces withan anchor indicator to communicate to a user sensed motion of theelectrical microstimulator under the influence of the predeterminedlongitudinal testing force.
 17. The apparatus of claim 16, wherein thesensed motion of the electrical microstimulator is sensed entirelymechanically.
 18. The apparatus of claim 16, wherein the sensed motionof the electrical microstimulator is sensed at least partiallyelectrically, through the use of a proximity sensor.
 19. The apparatusof claim 13, wherein the microstimulator docking feature includes aplurality of arms for splaying laterally inward and outward,respectively, as the delivery sheath moves toward and away from thedistal rod end.
 20. The apparatus of claim 13, wherein the arm includesa distal arm end engager for selective engagement with a correspondingdocking feature of the electrical microstimulator.
 21. The apparatus ofclaim 13, including a patient tissue sensor associated with the deliveryrod and communicating to a user information about a patient tissueadjacent to the distal rod end.
 22. The apparatus of claim 13, includinga sheath lock to selectively prevent longitudinal motion of the deliverysheath with respect to the handle body.
 23. The apparatus of claim 13,wherein the distal rod end is at least one of flexible, deflectable andblunt such that the delivery rod is deflected by a deep fascia layer toremain above the deep fascia layer.